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Poster: Administrator, Curator, or Stafflibrivoxbooks Date: Feb 6, 2013 2:53pm
Forum: audio_bookspoetry Subject: Re: Reduction in volume in derived files

The 128 kbps files that we upload to IA are produced using a variety of recording software. The majority of readers use Audacity, which definitely uses the LAME encoder (various flavours according to whether Mac or Windows) to produce the 128 kbps MP3. The LAME encoder recommended for the current Audacity version (2.0.x) is LAME v3.99.3.

The example file above was recorded in Audacity 1.3.14 and encoded with LAME v.3.98.4.

Ruth

This post was modified by librivoxbooks on 2013-02-06 22:53:16

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Poster: Administrator, Curator, or StaffJeff Kaplan Date: Feb 6, 2013 2:58pm
Forum: audio_bookspoetry Subject: Re: Reduction in volume in derived files

forgive me. what are you using to convert the 128kbps to 64kbps mp3 and 64 kbps ogg that is not resulting in db reduction?

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Poster: Administrator, Curator, or Stafflibrivoxbooks Date: Feb 6, 2013 4:22pm
Forum: audio_bookspoetry Subject: Re: Reduction in volume in derived files

Oh, sorry. I misunderstood. For OGG: MP3 WMA OGG Converter 9.0.1 which uses Lavf52.93.0 encoder, I think. For 64kbps MP3 I used online-convert.com.

Both these came out with 89 dB from the original 89.5 dB 128 kbps. Other testers, I imagine, used different methods with similar results - just 0.3 - 0.5 dB reduction in volume. I can probably find out what they used, if it will help?

ETA If it means anything, I also resampled at 22 KHz and exported at 64 kbps in Audacity (the 128 is sampled at 44 KHz), and there was no volume difference.

Ruth



This post was modified by librivoxbooks on 2013-02-07 00:22:01

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Poster: Administrator, Curator, or Stafflibrivoxbooks Date: Feb 13, 2013 9:19am
Forum: audio_bookspoetry Subject: Re: Reduction in volume in derived files

I wondered if there were any progress on this, Jeff? I didn't understand the earlier comment "the engineer here suspects it's due to a lower bitrate." I had wondered if he meant sample rate, which is why I tried resampling at 22 KHz as in my post below, but that didn't cause a drop in volume either.

Ruth

This post was modified by librivoxbooks on 2013-02-13 17:19:16

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Poster: Administrator, Curator, or StaffJeff Kaplan Date: Feb 15, 2013 9:59am
Forum: audio_bookspoetry Subject: Re: Reduction in volume in derived files

we'll review it when there is time. i can't tell you when that will be. from a quick check it looks like something changed on 2011-11-06. prior to that the 64kb mp3s were very similar in volume to the 128kb mp3s

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Poster: Administrator, Curator, or Stafflibrivoxbooks Date: Jul 14, 2013 1:56am
Forum: audio_bookspoetry Subject: Re: Reduction in volume in derived files

Is this still in a queue for attention, please? It's been a while ;).

Ruth

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Poster: Administrator, Curator, or Stafflibrivoxbooks Date: Feb 15, 2013 2:10pm
Forum: audio_bookspoetry Subject: Re: Reduction in volume in derived files

Thank you! :)

Ruth